The pattern of the wet spots on Selden Clark's suit changes.
Ann Powell's character hold a gun in her left hand in the cabin and then in her right later in the film.
When several characters are engaged in phone calls, as when Patricia, talks to Deborah, it is evident from the speaker's voice and stance, and the way the shot is composed, that there is someone else in the room listening to the conversation, as well (Selden, in this example). The other person is seen when the call ends, but it is of little surprise they were there all along given the cues that indicated their presence there, during the call.